In satellite communication systems, multibeam satellites are used for increasing the system capacity. In order to improve the frequency reuse factor without significantly increasing the interference, adjacent beams usually make use of the same frequency with different polarizations. In the adjacent beams, independent signals may be transmitted onto the same frequency band by means of two orthogonal polarizations, like for example horizontal and vertical polarizations. Impairments appear when the polarized waveform travels through the troposphere. Besides waveform attenuation, rain and ice depolarization effects are also present and the orthogonality may be lost, which leads to crosstalk between the two polarizations.
The severity of this effect depends on the operating frequency, atmospheric conditions, correct antenna calibration/alignment, etc.
Crosspolar interference causes performance degradation for the users able to receive both signals.
Mitigation techniques may be employed in order to reduce crosspolar interference. Many such techniques already exist in the literature, for example, joint minimum mean square error detection, with or without successive interference cancellation, turbo receivers.
The existence and the nature of the interferer need to be known in order for the mitigation techniques to be efficient.